Electric rectifier construction



Patented Sept. 11, 1934 s ,c has ELECTRIC RECTIFIER, CONSTRUCTION @skarSeit z, Baden, Switzerland, assignor to Aliticngesellschaft Brown Boveri& Cie., Baden, Switzerland, a joint-stock company of SwitzerlandApplication June 20, 1931, Serial No. 545,663

2 Claims.

This invention relates to improvements in electric power rectifiers ofthe metal tank enclosed metallic vapor type and particularly to aconstruction for retaining the cathode material 5 therein.

Electric power rectifiers of the present time are built with metal tankswhich are double-walled to permit the circulation of the cooling fluidin the space within the walls. The cathode material is retained within awell which is usually formed from a cylinder of insulating materialabutting against the tank bottom about an aperture therethrough. Theopen lower end of the cylinder is closed by a plate which may also bemade hollow to permit the circulation of acooling medium therethrough.

Due to the fact that an electric current rectifier of the metallic vaportype must be exhausted to a high degree of evacuation and that suchevacuation must be maintained while the rectifier is in operation, it isnecessary that the joints between the insulation and the metal portionsbe gas-tight. To secure such gas-tight joints, the insulation and metalportions are pressed tightly together thereby highly stressing theinsulation which is usually porcelain because of its insulating andheat-resistive qualities. Such stresses, particularly when theporcelains are heated, cause chipping, cracking and even completedestruction of the porcelain cylinder. To produce the necessarygas-tight joints, it is likewise necessary to provide elaborate seals,the most successful of which is a wellknown mercury seal.

It is, therefore, among the objects of the present invention to providea cathode well construction for electric power rectifiers in which theuse of insulation material as a portion of the tank structure isrestricted to its use as gaskets be tween metallic portions.

Another object of the invention is to provide a cathode retainingconstruction for electric power rectifiers which will have only a singlejoint in the cathode well and which joint will be unaffected by anystresses exerted thereon.

Another object of the invention is to provide a cathode wellconstruction for electric power rectifiers in which the single jointpresent in the cathode well construction is sealed merely by a gasket ofcompressible material.

Another object of the invention is to provide a structure arranged andretained internally within the cathode retaining structure of an electlc power rectifier for the purpose of protecting a compressible gasketarranged between the metallic portions of the structure from heat andother destructive forces exerted thereon.

Objects and advantages, other than those above set forth, will beapparent from the following description when read in connection with theaccompanying drawing, of which:

Fig. 1 is a vertical cross section through a cathode well embodying thepresent invention; and

Fig. 2 is a fragmentary vertical cross sectional View illustrating, inenlarged scale, the assem bled relation of certain of the elements shownin Fig. 1.

Referring more particularly to the drawing by characters of reference,the reference numeral 1 designates a portion of the double-walled bottomof a tank forming the enclosure for the anodes, etc. of an electricpower rectifier as is well-known. An aperture is formed in the tankbottom 1 and the double walls of the bottom are sealed by a ring 2thereby closing the opening between the walls and forming a space forthe circulation of a cooling medium therethrough. The ring 2 is formedwith a seat to receive a resilient gasket 3 which seals the jointbetween the ring 2 and a cathode plate 4. The plate 4 is drawn tightlyagainst the gasket 3 by bolts 6 passing through the plate and into thering 2. All of the elaborate seals heretofore considered necessary arethus avoided and the use of an extensive cylinder of relatively fragileinsulating material is not required. The plate 4 is preferably madedoublewalled as shown and is supplied with a suitable cooling mediumthrough an inlet '7. The cooling medium is circulated by permitting theescape thereof through an outlet pipe 8.

The cathode plate 4 forming the cathode well proper retains a quantityof vaporizaole conductive material 9, such as mercury, forming thecathode to which the arc attaches. A suiiicient quantity of mercury ispresent to permit retention of some mercury within the well even at themaximum vaporization rate of the rectifier during operation. The mercurycondensed on the cooled tank wall is returned to the cathode well as isusual.

To permit the use of materials injuriously affected by heat as thegasket 3, a cylinder 11 of suitable heat resistive material such asquartz is retained within the cathode plate. The ground upper edge ofthe cylinder 11 is resiliently retained in close contact with a seatformed in a relatively heavy plate 12 of a material not af fected by thevapor rising from the cathode. The plate 12 is held in spaced relationfrom the bottom 1 by a ring 13 fastened thereto by bolts passing throughboth the plate 12 and the ring 13 into the tank bottom wall 1. An arcflowing from the anodes (not shown) to the cathode is thus preventedfrom passing behind the cylinder ll thereby injuring the gasket and islikewise prevented from attaching on the upwardly extending portion ofthe cathode plate 4 which would be damaged or destroyed thereby.

The cylinder 11 is pressed upwardly against the protective plate 12 bymeans of helical springs 15 resting recesses formed in th cathode platea. The springs are provided with caps 17 to prevent uneven seating oithe cylinder on the spring and to aid in guiding the expansion andcompression movements of the spring.

A strap 18 is secured in spaced relation along a portion of the edge ofthe cap, and a strap 21 having a bow-shaped leaf spring 22 securedthereto at right angles to the axis of the strap 21 is passed betweenthe top of the cap 17 and the strap 18. When the cylinder 11 is properlyplaced on the springs, the straps 21 are so adjusted by bending the endsthereof over the edges of the caps as to produce a slight springpressure on the cylinder from all sides thereby aiding in maintainingthe cylinder in a centered position.

Although but one embodiment of the present invention has beenillustrated and described, it

will be apparent to those skilled in the art that various changes andmodifications may be made therein without departing from the spirit ofthe invention or from the scope of the appended claims. 7

The invention claimed is:

1. In an electric current rectifier, the combination of a casing ofelectrically conductive material having an aperture through the bottomthereof,

a receptacle containing vaporizable electrode material supported on saidcasing and closing said aperture therein, an annular plate supportedwithin said casing concentrically with said aperture and spacedtherefrom, a cylinder of insulating material supported withinsaid'aperture in contact with said plate and in contact with saidelectrode material, a plurality of springs arranged in spaced relationabout said cylinder for causing the latter to be yieldingly pressed intocontact with said plate, pressure equalizing and guiding membersarranged about said springs, and members resiliently affixing saidguiding members to said cylinder for supporting the latter within andconcentric with the said aperture.

2. In an electric current rectifier, the combination of a casing ofelectrically conductive material having an aperture through the bottomthereof, a receptacle containing vaporizable electrode materialsupported on said casing and closingthe aperture therein, saidreceptacle having a plurality of spaced recesses in the bottom wallthereof, an annular plate supported within said casing concentricallywith said aperture and spaced therefrom, a cylinder of insulatingmaterial supported within said aperture in contact with said plate andin contact with said electrode material, a plurality of springssupported within said recesses for caum'ng said cylinder to beyieldingly pressed into contact with said plate, pressure equalizing andguiding members arranged about said springs for supporting saidcylinder, and members resiliently affixing said guiding members to saidcylinder for maintaining said cylinder concentric with said aperture,the said cylinder being operable to guide arcs flowing to said electrodematerial and to limit the flow of heat from said material to the wallsof said receptacle.

OSKAR SEITZ.

